1. Field of the Invention
The present invention broadly relates to a method for preparing a meat product which not only renders it biologically stable but also organoleptically similar to freshly cooked meat chunks. The present invention particularly relates to a method for preparing an acidified meat product suitable for inclusion in heat-treated, though not sterilized, high acid liquid foods such as sauces, gravies and the like.
2. Description of the Prior Art
The majority of canned food products are sterilized by retorting the canned product at high temperatures. In this context, the term "sterilized" means that microorganisms which may pose a health hazzard, including spores which may cause spoilage, under normal nonrefrigerated storage conditions have been eradicated. Retorting involves heating a sealed container of the food product, in accordance with a well-defined time-temperature history, for a sufficient time to destroy (kill) all microbial material, particularly those pathogenic and toxin-forming microorganisms which potentially could flourish under the canned product's normal storage conditions. With proper treatment, such products can remain at room temperature substantially indefinitely without being spoiled or contaminated by microbial activity.
Some food products, however, undergo noticeable and undesirable organoleptic degradation when exposed to the severe heat processing conditions necessary to render the canned product biologically sterile. Included within this class of food products are certain pectin-containing foods, particularly tomato-based products including spaghetti sauce, taco sauce, chili sauce and the like.
Fortuitously. heat processing conditions required to produce a biologically acceptable product are known to vary with the food product's pH. For example, it is well known that food products having a low pH, below about 4.2 to 4.6, typically referred to as high acid foods, need only a mild heat treatment in order to obtain a biologically stable product, since acid-tolerant organisms responsible for food spoilage such as yeast and molds generally have a low temperature threshold. The tomato-based products mentioned above fall into the category of high acid foods. Other organisms, including spores, responsible for food spoilage and food borne illness which are only destroyed by a more severe temperature treatment, such as Clostridium botulinum and Bacillus coagulans, cannot germinate or grow in the low pH environment prevailing in such high acid foods. It is possible therefore to preserve the organoleptic quality of a high acid food product without sacrificing consumer safety by avoiding the severe heat treatment needed to destroy such heat resistant organisms and instead rely on the high acidity of the food product to insure biological stability by preventing spore germination and growth.
Based on this understanding, the prior art has developed a process wherein such high acid food products are heat treated under conditions which destroy acid-tolerant organisms and then the heated material is packaged before it cools. With this process the need to retort the packaged (canned) product is avoided. According to this technology, the high acid food, such as a spaghetti sauce, is thermally processed at a high enough temperature and for a period of time long enough to destroy acid-resistant organisms using heat exchanger equipment well known in the food processing industry. Typically, such products are heated to a temperature of about 190.degree. to 205.degree. F. The hot heat-treated product then is filled into a previously cleaned container under clean, though not biologically sterile, conditions. The container filled with the hot product is sealed and passed through a steam chamber so as to retard cooling of the hot-filled product for a short time period, long enough to ensure that all acid-resistant microbes are destroyed, typically about 3 minutes. The container then is cooled to yield a product suitable for marketing.
One disadvantage associated with these hot-filled, high acid liquid food products is that it is difficult to incorporate other low-acid and medium-acid solid food additives such as meat into the packaged product. The inclusion of such materials into the product tends to increase the overall pH of the packaged product making both the product and the additives prone to contamination and spoilage by heat-resistant organisms such as Clostridium botulinum and Bacillus coagulans.
U.S. Pat. No. 3,886,296 describes a process for including low-acid and medium-acid foods in a high-acid food product. According to the disclosed technique, the low-acid or medium-acid food, including meat, spaghetti and vegetables having a thickness of no more than about 0.5 inch, is subjected to a high temperature, acid blanch for a short time period so as to reduce the pH of the food to below about 5.0. The acid blanched food then is immersed in an acidic liquid phase such as a sauce or gravy having a pH below 4.5. Generally, the liquid phase is at an elevated temperature, e.g., on the order of 160.degree.-212.degree. F. The combined product is sealed in a container and then is heat processed at relatively low temperatures for short periods of time, for example on the order of about 10-15 minutes at or below 212.degree. F. (mild retort). The patent discloses that due to the acid blanching of the food and the fact that the food is submerged in an acidic liquid phase, the food particles acquire an overall pH of 4.5 or below within about 30 minutes after the food particles and the acidic liquid phase are combined.
The process of U.S. Pat. No. 3,886,296 typically is not suitable for acidification of meat chunks, i.e., meat pieces having a dimension of about 0.5 inch or larger, to a pH below about 4.6, since acidification from the acid blanch is a relatively slow process limited by the rate of hydronium ion diffusion into the meat. Such diffusion is influenced by both the size and physical characteristics of the meat. The art has recognized, see U.S. Pat. No. 4,262,027, that unless the meat particles are small in size, it is difficult to obtain a uniform distribution of acid throughout the meat. U.S. Pat. No. 4,262,027 itself attempts to remedy this problem by forming a meat emulsion containing an acidogen which reduces the pH of the emulsion when it is cooked by forming an acid in situ so as to produce the desired acidified meat product. Notably, both U.S. Pat. Nos. 3,886,296 and 4,262,027 only disclose using the acidified food product in a canned product that is subsequently retorted, even though the retorting is done under a mild time-temperature history.
It is an object of the present invention to provide a process for preparing an acidified meat product suitable for inclusion in a heat treated, though not retorted and sterilized, high acid-type liquid product such as sauce, gravy and the like.
It is another object of the present invention to provide a process for preparing a uniquely structured acidified meat product that is organoleptically similar to freshly cooked meat chunks.
These and other objects of the present invention will become apparent from a consideration of the specification and appended claims.